Quantitative correlation of infrared absorption with nuclear magnetic resonance measurements of hydrogen content in diamond films

Abstract

Hydrogen concentrations in polycrystalline diamond films were found to correlate well with the integrated intensity of the CH-stretch region in the infrared (IR) spectrum for films with a total hydrogen content <0.10 at. %. Comparison of IR to nuclear magnetic resonance (NMR) measurements yielded an effective absorption coefficient for the CH-stretch region of 4.3±0.8×103 ℓ mol−1 cm−2, similar to literature values for condensed-phase hydrocarbons. In several films, the dominant stretch modes occur at ∼2850 and 2920 cm−1, typical of CH2 groups. The presence of these modes is accompanied by an increase in the Gaussian linewidth in the NMR spectrum, indicating a decrease in the interproton spacings within the film. In films with higher total hydrogen contents, a simple linear relationship between hydrogen content and intensity in the CH-stretch region is no longer applicable.